Custom signage articles of all sizes are often made with relief surfaces. Such relief surfaces can have variable depths formed by abrasive etching, acid etching, machining, or other techniques. For example, it is possible to use photoresist layers and abrasives to make an etched surface for use in signs.
Existing methods of producing relief surfaces are often imprecise in terms of controlling surface relief. The equipment operator needs to show great care in controlling relief depth, typically by regulating abrasion rate (controlled by amount of abrasive, size of abrasive, and speed of abrasive particles) as well as duration of time at which an area is exposed to abrasion. These inexact controls can be adequate for some purposes, but are not sufficient for those requiring precise depths of the relief.
An example of a type of signage requiring relatively high depth precision are signs incorporating Braille characters. Braille is a system by which people with limited or no vision can use tactile senses to read letters written in an alphabet of raised dots. Regulations regarding Braille signage are provided by the United States Access Board in the Americans with Disabilities Act (ADA) and Architectural Barriers Act Accessibility Guidelines (Jul. 23, 2004), Section 703. These guidelines state that all raised characters must be a minimum of 1/32″ in height above their background and Braille dots must be 0.025-0.037″ in height and have a domed or rounded surface. Existing abrasives etching techniques are not generally suitable for precisely producing Braille dots of such height.
Therefore, a need exists for an improved method of making-signage with precise and controlled feature heights, such as Braille characters.